The characteristic of being unfaithful; infidelity; disloyalty.(noun)
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Use "unfaithfulness" in a sentence
"The great apology for what I call unfaithfulness to employers, is,"
"After all, the Bible expressly says that what God has joined no man should put asunder and that anyone who divorces except for reasons of unfaithfulness is committing adultery."
"In all my years "cheating" and "unfaithfulness" is becoming more and more frequent."